如何在提交後將字段值保存在表單中？

Question

提交表單後，字段值顯示爲空白。我正在做一些表單驗證;如果表單無效，我會從錯誤列表中顯示錯誤消息，但我希望字段值保留。有沒有辦法做到這一點？

這是我的觀點，即驗證表單：

@app.route('/booking', methods=['GET', 'POST']) 
def booking(): 
    errors = [] 
    if request.method == 'GET':  
     return render_template('booking.html', errors=errors) 
    else: 
     # grab values from form fields and store them in objects 
     start_date = request.form['start_date'] 
     end_date = request.form['end_date'] 
     name = request.form['name'].strip() 
     email = request.form['email'].strip()  

     # check if all fields are non-empty and raise an error if not 
     if not start_date or not end_date or not name or not email: 
      errors.append('Please enter all the fields.') 
     else: 
      # converts dates to Unix time-stamp for easier validation/calculations 
      start_timestamp = dt.strptime(start_date, "%d/%m/%Y") 
      end_timestamp = dt.strptime(end_date, "%d/%m/%Y") 

      # checks to see if dates are valid   
      if start_timestamp > end_timestamp or end_timestamp < start_timestamp:    
       errors.append('Please enter a valid date range') 
      else: 
       #checks to see if booking has already been taken 
       bookings = read_file('app/static/bookings.csv')  
       for i in bookings: 
        s_date = dt.strptime(i[0], "%d/%m/%Y") 
        e_date = dt.strptime(i[1], "%d/%m/%Y") 
        if s_date <= start_timestamp <= e_date: 
         errors.append('Booking has already been taken, please select another date') 
         break 

      # checks to see if email address is valid using regex 
      if not valid_email_address(email): 
       errors.append('Please enter a valid email address')   

      #if no errors have occured then write booking to file 
      if not errors: 
       new_booking = [start_date, end_date, name, email] 
       bookings.append(new_booking) 
       write_file(bookings, 'app/static/bookings.csv') 
       return render_template('booking.html') 
    return render_template('booking.html', errors=errors) 

這是表單模板：

<div id="main-wrapper"> 
    <div id="main">  
     <div id="info"> 
      {% if errors %} 
      {% for error in errors %} 
      <div><p>{{ error }}</p></div> 
      {% endfor %} 
      {% endif %} 
      <form action = "booking" method="post"> 
      <input id="start_date" type="text" name="start_date"> 
      <input id="end_date" type="text" name="end_date"> 
      <input type="text" name="name" /> 
      <input type="text" name="email" /> 

      <input type="submit" value="Submit"> 
     </div> 
    </div> 
</div> 

Answer 1

你會更好使用表單庫如WTForms （和相關的分機號Flask-WTF），而不是手動完成。

但是，如果你設置了這個方法，那麼它非常簡單。您需要將request.form中的值提供給HTML輸入。

<input id="start_data" type="text" name="start_date" value="{{ request.form['start_date'] }}"/>